I used a 6in drain cover. I think it's a PVC type plastic. I used a router to cut all the grid stuff out. then I just used some silicone sealer to stick a piece of plexy to the bottom. I cut the plexy glass circle with the router too. Works great 6in view window. All made for less then 10bucks and a short trip to home depo.
I got a submersible bag type thing for my p&s... Works awesome!! We got it to take to st. Martin a few years ago. Really cheap it was an eBay items but it worked! took it down 30ft when we went scuba diving and it held air tite... They fit most small p&s cams..